`debug_info` for system components leak `comp_dir` when using `zig cc`

[Bownairo]

Zig Version

0.14.0

Steps to Reproduce and Observed Behavior

When building with zig cc and preserving debug_info, there does not seem to be any way to replace the comp_dir for system components (crt, libc, libunwind, etc.) around here.

---

For example, when using zig cc and Rust:

$ RUSTFLAGS="--remap-path-prefix=$(pwd)=. -C strip=none" cargo build

In the resulting binary, units built outside of zig are cleaned:

$ readelf --debug-dump=info target/debug/dummy
...
    <153>   DW_AT_name        : (indirect string, offset: 0x108ed6): src/main.rs/@/1l91654gzite33ik2xmzykra6
    <157>   DW_AT_stmt_list   : 0x152
    <15b>   DW_AT_comp_dir    : (indirect string, offset: 0x487a0): .
...

But these system components leak comp_dir:

$ readelf --debug-dump=info target/debug/dummy
...
    <20>   DW_AT_name        : /home/ubuntu/zig-linux-x86_64-0.14.0/lib/libc/glibc/sysdeps/x86_64/start.S
    <6b>   DW_AT_comp_dir    : /home/ubuntu/dummy
...

Expected Behavior

Some configuration path to pass args to the SubCompilation stage, from zig cc.